Light the oven, get out the brown sugar, and you are in for a special pineapple treat.
Preheat oven to 400 degrees, with rack in upper third. Using a chef's knife, slice off top and bottom ends of pineapple. Following the fruit's natural shape and working from top to bottom, slice off skin in strips; cut away any "eyes." Quarter lengthwise; remove tough core. Cut each quarter into 4 pieces lengthwise.
Place butter in an 8-inch square (2-quart) baking dish, and melt in oven, 6 minutes.
Arrange pineapple in the dish. In a small bowl, stir together brown sugar, honey, pie spice, and rum.
Spoon sugar mixture over pineapple. Bake until tender and bubbly, about 1 hour. Serve warm or at room temperature with sorbet, if desired.